I don't use that sort of bin but I have read here that it is pretty common to have worms exploring down there.

The drainage that comes out the bottom is called leachant and doesn't have much nutritional value. I think most people use it to dampen the bedding if needed or just water some plants with it.

Marshall

Mine were going downstairs the last 2 weeks too and now they are above the compost crawling around the walls of the bucket containers I use. No idea for their change of positions other than I added alot more organic food waste than typical a few days ago. I had been picking them out of the drainage basement and popping them back in the top bucket. Maybe they got the idea to stay out of there. :)

Greetings,
I have a similar, but home made, flow through type worm bin and have the same problem of the worms gathering in the sump / swamp. What I have resorted to doing (and it seems to be quite successful) is to put dry shredded paper down there and fortnightly dump worms and sludge back into the top working level. This helps absorb excess moisture and gives those wayward worms some work to do whilst on vacation. It however does not stop the cycle. It happens in all my bins of this type and does not appear to be food or population dependant.
Regards,
John K

To tell you the truthm the worms down there are probably going to DIE or near death already.
Thing is, I'm not sure how lonh worms live or maybe jsut some give up while living inside a cubic foot prison of thrown out wastes from the Global system.
But the thing is, there's 7 worms to one, with the wise gardener.
A worm sacrificed is even more earned. SO it's heard. Just expand when possible and keep adding food, and don't worry about the worms down in the water.

Have a quick look here at the Video link below.

Doesn't address your problem, but showcases the Wriggly Ranch rather well.

Cheers

Here is a link that might be useful: Wriggly Wranch videos